Donuts:

Make the Dough

1. Add flour and yeast to the bowl of a stand mixer fitted with the dough hook and mix for a few seconds to combine. Add all remaining ingredients except for the butter and mix on low speed for a few minutes until everything is incorporated. With the mixer on low speed, add the butter a few pieces at a time. Stop and scrape the bottom and sides of bowl to make sure everything gets incorporated and then continue mixing on a low to medium speed for another 5 minutes.
2. Remove dough from bowl and place on a clean and well floured work surface, the dough will be sticky. Use your hand to gently pat the dough into a rectangle shape. Stretch the left side of the dough inward over about 2/3 of the dough and then fold the right side inward toward the center, as if you were folding a letter. Repeat this process, shaping into a rectangle and folding over, one more time, but folding from the top and bottom this time.
3. Spray a large bowl with non-stick spray. Place the dough, seam side down, in the bowl and cover with a clean towel or plastic wrap. Let rise at room temperature for 1 hour.
4. Place dough again on a floured surface and once again repeat the stretching and folding process from above. Once done, return the dough to the bowl, cover, and let rest in the fridge overnight.

Roll Out, Shape and Proof

1. On a floured surface, roll out dough to about 1/2 inch thick. Line a sheet pan with parchment paper and lightly spray with non-stick spray. Using a 3 inch circle cutter, cut out about 10 donuts and place on the prepared pan. If desired, use the scrapes to make donut holes, using a 1 1/2 inch circle cutter.
2. Cover lightly with plastic wrap and let the cut donuts proof at room temperature for 1 to 1 1/2 hours, until doubled in size.

Fry

1. Pour at least 3 inches of oil into a large stockpot. The oil should be deep enough to allow the donuts to float freely in the pot. Heat the oil to 335°F – 345°F. Place a cooling rack over a baking sheet.
2. Gently fry 3-4 donuts at a time, about 2-3 minutes per side, until they have developed a deep golden brown color. Transfer cooked donuts to the cooling rack and let cool for a minute or two before rolling in the strawberry sugar. Repeat with remaining donuts. Fry donut holes for only about 1 minute per side.

Strawberry Sugar:

1. In a food processor, pulse freeze dried strawberries until they are in a similar size as the sugar. Sift the strawberries into the sugar to remove any large pieces. Stir together sugar and strawberries.

Strawberry Rhubarb Filling:

1. Place the fruit and sugar into a small sauce pan. Cook the mixture over medium heat until the fruit begins to break down and simmer, about 5-10 min.
2. Whisk together the lemon juice and corn starch until the corn starch is dissolved. Reduce the heat to medium-low and add the lemon juice/corn starch slurry. Cook for 1-2 minutes more. Remove from heat and use an immersion blender to puree. Let cool, cover, and refrigerate until ready to use. Mixture will thicken some.

Fill the Donuts:

1. Once the donuts are completely cooled make a small slit on the side of each donut. Fit a pastry bag with a small round piping tip and fill the bag with the strawberry rhubarb filling. Place the pastry tip into the side of the donut and gently fill until the donut starts to feel heavy and the filling starts oozing out.